The St. Louis Business Journal quotes at length from a legal opinion authored by David Roland, Michael Wolff, and Winston Calvert:
An opinion addressed to Green by Winston Calvert, former city counselor, David Roland, director of litigation at the Freedom Center of Missouri, and Michael Wolff, dean emeritus of Saint Louis University Law School, said there are a number of other state statutes that are rarely investigated or enforced by local law enforcement.
“The proposed Ordinance does not decriminalize possession and use of marijuana — federal and state laws are still in force,” their letter said. “Rather the Ordinance prohibits City law enforcement officials from using City resources to enforce those prohibitions against responsible adults.”
They also said it’s possible the state or federal governments could challenge the ordinance, and the state could attempt to pass a law that would require local governments to enforce marijuana prohibitions.
“Such an effort would raise the question of whether the state has the authority to obligate cities to direct their local resources in a manner that the city has chosen not to do,” the letter said. “If the state attempts to require the City to enforce marijuana prohibitions it is possible that the Hancock Amendment would require the state pay for such enforcement actions.”